# [postgis-users] Area calculation oh two polygon that they are overlapping

olivier.amram at free.fr olivier.amram at free.fr
Thu Jan 10 08:23:45 PST 2008

```Yes, but how do you calculate the area of the intersection ?

Olivier.

Selon Guido Lemoine <guido.lemoine at jrc.it>:

> Your multipolygon is simply two rings of 3 by 3. Defining them
> as multipolygon does do nothing for intersection, so the area is 18
> (which is 9 + 9). You need to look up what intersection means.
> For me, the intersection of the 2 polygons is the common area,
> which is 4.
>
> GL
>
> olivier.amram at free.fr wrote:
> > Hi,
> >
> > I'd like to compute the total area of polygon that intersects with another
> > polygon
> >
> > Polygon(0 0,0 3,3 3,3 0,0 0)
> > Polygon(1 1,4 1,4 4,1 4,1 1)
> >
> > The total area is 14 but I don't find a solution to compute this value.
> >
> > e.g. SELECT Area(GeomFromText('MultiPolygon( ((0 0,0 3,3 3,3 0,0 0)),((1
> 1,1 4,4
> > 4,4 1,1 1)))')) --> 18
> >
> > Have you any idea ?
> >
> > Thank,
> >
> > Olivier.
> >
> > _______________________________________________
> > postgis-users mailing list
> > postgis-users at postgis.refractions.net
> > http://postgis.refractions.net/mailman/listinfo/postgis-users
> >
> >
>
> --
> ----------------------------------------------------------------
> Guido Lemoine
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```